Android framework ATMS启动流程

public static void main(String[] args) {
    new SystemServer().run();
}

private void run() {
	try {
		...
		// 创建Looper
		Looper.prepareMainLooper();
		// 加载libandroid_servers.so
		System.loadLibrary("android_servers");
		// 创建系统的 Context：ContextImpl.createSystemContext(new ActivityThread())
		createSystemContext();
		// 创建 SystemServiceManager
		mSystemServiceManager = new SystemServiceManager(mSystemContext);
		LocalServices.addService(SystemServiceManager.class, mSystemServiceManager);
		...
	}
	...
	try {
		//启动引导服务，ActivityManagerService、ActivityTaskManagerService、PackageManagerService、PowerManagerService、DisplayManagerService 等
		startBootstrapServices(); 
		//启动核心服务，BatteryService、UsageStatusService 等
		startCoreServices(); 
		//启动其他服务，InputManagerService、WindowManagerService、CameraService、AlarmManagerService 等
		startOtherServices(); 
		...
	}
	...
	// 开启消息循环
	Looper.loop();
}

private void startBootstrapServices() {
	...
    //启动 ATMS
	ActivityTaskManagerService atm = mSystemServiceManager.startService(ActivityTaskManagerService.Lifecycle.class).getService();
    //启动 AMS，并将 ATMS 注入
	mActivityManagerService = ActivityManagerService.Lifecycle.startService(mSystemServiceManager, atm);
	...
}

public <T extends SystemService> T startService(Class<T> serviceClass) {
	try {
		final String name = serviceClass.getName();
		...
		final T service;
		try { //通过反射调用 serviceClass 的构造方法 创建 Lifecycle 对象
			Constructor<T> constructor = serviceClass.getConstructor(Context.class);
			service = constructor.newInstance(mContext);
		}
		...
		startService(service);
		return service;
	}
	...
}

public void startService(SystemService service) {
	mServices.add(service); //mServices: ArrayList<SystemService>
	...
	try {
		service.onStart(); //调用 Lifecycle 的 onStart 方法
	}
	...
}

public static final class Lifecycle extends SystemService {
	private final ActivityTaskManagerService mService;

	public Lifecycle(Context context) {//被 SystemServiceManager 的 startService() 方法调用
		super(context);
		mService = new ActivityTaskManagerService(context);
	}

	public void onStart() {
        //添加 ATMS 服务，方便跨进程调用：ServiceManager.addService(Context.ACTIVITY_TASK_SERVICE, mService, false, DUMP_FLAG_PRIORITY_DEFAULT)
		publishBinderService(Context.ACTIVITY_TASK_SERVICE, mService);
		mService.start(); //调用 ATMS 的 start() 方法
	}
	
	...

	public ActivityTaskManagerService getService() {
		return mService;
	}
}

IBinder b = ServiceManager.getService(Context.ACTIVITY_TASK_SERVICE); 
IActivityTaskManager atm = IActivityTaskManager.Stub.asInterface(b);

public ActivityTaskManagerService(Context context) {
	mContext = context;
	...
	mSystemThread = ActivityThread.currentActivityThread();
	mUiContext = mSystemThread.getSystemUiContext(); //ContextImpl.createSystemUiContext(getSystemContext())
	mLifecycleManager = new ClientLifecycleManager();
	mInternal = new LocalService(); //ActivityTaskManagerInternal 的子类
	...
}

private void start() {
	LocalServices.addService(ActivityTaskManagerInternal.class, mInternal);
}

public ActivityManagerService(Context systemContext, ActivityTaskManagerService atm) {
	...
	mHandlerThread = new ServiceThread(TAG, THREAD_PRIORITY_FOREGROUND, false);
    ...
    mUserController = new UserController(this);
	mPendingIntentController = new PendingIntentController(mHandlerThread.getLooper(), mUserController);
	...
	mIntentFirewall = new IntentFirewall(new IntentFirewallInterface(), mHandler);
	mActivityTaskManager = atm;
	//进一步初始化 ATMS
	mActivityTaskManager.initialize(mIntentFirewall, mPendingIntentController, DisplayThread.get().getLooper());
	...
}

public void initialize(IntentFirewall intentFirewall, PendingIntentController intentController, Looper looper) {
	mH = new H(looper);
	mUiHandler = new UiHandler();
	mIntentFirewall = intentFirewall;
	...
	mPendingIntentController = intentController;
	mTempConfig.setToDefaults(); //定义时即被创建：mTempConfig = new Configuration()
	...
	//new ActivityStackSupervisor(this, mH.getLooper())
	mStackSupervisor = createStackSupervisor(); 
	mRootActivityContainer = new RootActivityContainer(this);
	mRootActivityContainer.onConfigurationChanged(mTempConfig);
	...
	mLockTaskController = new LockTaskController(mContext, mStackSupervisor, mH);
	mActivityStartController = new ActivityStartController(this);
	mRecentTasks = createRecentTasks(); //new RecentTasks(this, mStackSupervisor)
	mStackSupervisor.setRecentTasks(mRecentTasks);
	...
}

private void start() {
	...
	LocalServices.addService(ActivityManagerInternal.class, new LocalService());
    //调用 ATMS 的 onActivityManagerInternalAdded 方法进一步初始化
	mActivityTaskManager.onActivityManagerInternalAdded();
	mUgmInternal.onActivityManagerInternalAdded();
	mPendingIntentController.onActivityManagerInternalAdded();
	...
}

public void onActivityManagerInternalAdded() {
	synchronized (mGlobalLock) {
		mAmInternal = LocalServices.getService(ActivityManagerInternal.class);
		mUgmInternal = LocalServices.getService(UriGrantsManagerInternal.class);
	}
}

ActivityStartController(ActivityTaskManagerService service) {
	this(service, service.mStackSupervisor,
			new DefaultFactory(service, service.mStackSupervisor,
				new ActivityStartInterceptor(service, service.mStackSupervisor)));
}

ActivityStartController(ActivityTaskManagerService service, ActivityStackSupervisor supervisor,
		Factory factory) {
	mService = service;
	mSupervisor = supervisor;
	mHandler = new StartHandler(mService.mH.getLooper());
	mFactory = factory;
	mFactory.setController(this);
	...
}

static class DefaultFactory implements Factory {
	...
	private ActivityStartController mController;
	private ActivityTaskManagerService mService;
	private ActivityStackSupervisor mSupervisor;
	private ActivityStartInterceptor mInterceptor;
	
	//MAX_STARTER_COUNT = 3
	private SynchronizedPool<ActivityStarter> mStarterPool = new SynchronizedPool<>(MAX_STARTER_COUNT);

	DefaultFactory(ActivityTaskManagerService service, ActivityStackSupervisor supervisor, ActivityStartInterceptor interceptor) {
		mService = service;
		mSupervisor = supervisor;
		mInterceptor = interceptor;
	}

	public ActivityStarter obtain() {
		ActivityStarter starter = mStarterPool.acquire();
		if (starter == null) {
			starter = new ActivityStarter(mController, mService, mSupervisor, mInterceptor);
		}
		return starter;
	}

	@Override
	public void recycle(ActivityStarter starter) {
		mStarterPool.release(starter);
	}
}